Redis is an open source memory-based key-value storage system, commonly used in scenarios such as caching, queuing, and real-time data processing. In large-scale applications, in order to improve the availability and performance of Redis, it is often necessary to adopt a distributed architecture, in which master-slave replication is a commonly used mechanism.
This article will introduce the master-slave replication function of Redis, including definition, principle, configuration and application scenarios.
1. Definition
The master-slave replication of Redis refers to automatically synchronizing the data of one Redis node (ie the master node) to other nodes (ie the slave node) to achieve data replication and load balanced purpose. The master node is responsible for write operations, and the slave node is responsible for read operations; when the master node fails, the slave node can take over from the master node and continue running, thereby improving the availability and fault tolerance of Redis.
2. Principle
Redis’ master-slave replication is based on the asynchronous replication mechanism. When the master node receives a write operation, it will encapsulate the write command into an RDB file or AOF file, save it to the disk, and execute it in memory. At the same time, the master node broadcasts the write command to all slave nodes to achieve synchronous update of data.
After receiving the broadcast command from the master node, the slave node will parse and execute the command, and reply the execution result to the master node. The master node will confirm or resend based on the feedback from the slave node.
Since master-slave replication is based on an asynchronous replication mechanism, there is a data delay to a certain extent, that is, the data of the slave node is not necessarily exactly the same as the data of the master node. In addition, when the master node fails, data inconsistency and loss may occur.
3. Configuration
Redis’ master-slave replication requires relevant configuration, including the startup parameters and configuration files of the master node and slave node, etc.
The master node needs to set the following parameters in the configuration file:
# 设置节点的名称为“mymaster” slaveof no one port 6379 pidfile /var/run/redis/redis-server.pid logfile /var/log/redis/redis-server.log
The slave node needs to set the following parameters in the configuration file:
# 设置节点的名称为“myslave” slaveof mymaster 6379 port 6380 pidfile /var/run/redis/redis-server.pid logfile /var/log/redis/redis-server.log
Among them, the slaveof parameter specifies the master node name and port number to which the slave node is connected; the port parameter specifies the listening port number of the slave node; the pidfile parameter Specify the save file of the process ID; the logfile parameter specifies the save path of the log file.
4. Application Scenarios
The master-slave replication function of Redis is widely used in the following scenarios:
5. Summary
Redis’ master-slave replication is a very useful distributed mechanism and plays an important role in Redis applications. This article provides a detailed introduction to the master-slave replication function of Redis, including definition, principle, configuration and application scenarios. I hope it can provide reference and help to readers.
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